The present invention relates to an apparatus and method for providing fire protection when drying clothes with heated air. Specifically, a fire protection system is described for a clothes dryer which includes a fire suppression system that is enabled by the dryer electronic controller based on signals received from temperature sensors which monitor the internal temperature of the dryer to determine whether a fire exists within the tumbler.
Conventional clothes dryers comprise a tumbling chamber into which a load of wet clothing is inserted. The chamber includes a tumbler which is rotated to effect tumbling of the clothes. In reversing type clothes dryers, the clothes may be tumbled in two directions. In either type of clothes dryer, a stream of hot air from an electric heater or gas fired burner, or steam heated air, is forced through the tumbler which removes the moisture contained in the clothing. Recently, microwave heated air has also been used to dry the clothes.
A particular problem in detecting fires in the tumbler occurs because fires may begin during drying, but not increase to a noticeable level until only after the dryers cycle is complete. Normal over temperatures exhaust conditions are monitored during drying, but once drying has ended, a smoldering load of dried clothes may remain undetected.
The present invention provides a method and apparatus for suppressing a fire within a clothes dryer. A fire protection system has temperature sensors or probes which monitor the internal temperature of the tumbler and enable the dryer electronic controller to determine whether a fire exists within the dryer. If a fire exists within the dryer, the electronic controller enables a fire suppression system to extinguish the fire.
In one embodiment of the clothes dryer of the present invention, the fire protection system may include a first sensor for producing a signal representing the internal temperature of the rotating clothes, and a second sensor for producing a signal representing the temperature of the exhaust air. The electronic controller is connected to the first and second sensors to determine from signals produced by the first and second temperature sensors whether a fire exists in the dryer, and subsequently enables the fire suppression system in response to the fire detection.
In an apparatus and method according to a preferred embodiment of the present invention, the electronic controller enables the fire suppression system if the temperature within the chamber is determined to be increasing and the temperature increase exceeds a threshold differential. When the fire suppression system is activated, the electronic controller may also enable the tumbling of the tumbler to avoid blockage of extinguishing material by a rib of the tumbler, and also to expose burning clothes to the fire suppression material. A timing interval may be utilized to disable the fire suppression system if the probe temperature no longer indicates that a fire is present within the tumbler.
In another embodiment according to the present invention, during the drying cycle, a sensor successively produces a signal representing the exhaust air of the clothes dryer. The electronic controller of the fire protection system enables the fire suppression system if the exhaust air temperature is above a specific set point, or if the exhaust air temperature exceeds a threshold differential compared to the cycle set point temperature of the dryer.